Houseflies with helminthic objects, a good indicator for unsanitary environment

Abstract

Houseflies are a mechanical vector of helminthic infections, and it is common to find all stages (egg-larvaadult) of helminths in flies. In communities where people harbor high prevalence of worm infection, and the use of outside latrines is common, houseflies may play an important role in the mode of transmission. People in the area with high contaminated flies are risk for many helminth infections due to Ascaris, Trichuris, Taenia and Angiostrongylus. For this study, helminth objects were compared from two study areas: Tak and Yasothon provinces in Thailand. In Tak province (western Thailand) where defecating in outside latrines is common, the prevalence of helminthiasis was 55.2%. The majority of infections were Ascaris (47.8%) and some villagers were even diagnosed with heavy ascaris infestation. Upon examination of 622 houseflies that were captured in this area, the number of eggs detected was as follows: 1,951 (Ascaris), 369 (Taenia), 147 (Trichuris), 52 (hookworm) and 1 (Toxocara). In Yasothon province (northeastern Thailand), indiscriminate defecation is rare, therefore the prevalence of helminthic infection was low with no observances of ascaris infection among the population. Examination of houseflies showed that Dicrocoelium eggs were common and other eggs such as Strongyloides, Trichuris and Opisthorchis were also noted. These eggs are commonly found in dogs and cats so it is possible that they belonged to animal parasites. T he examination of helminth objects on the external body of houseflies can be performed easily and the agents can be examined by using a light microscope. This simple method can be used as an indicator of an environment’s unsanitary condition caused by human and animal waste.